Right, if you had applied the Animasl tag to some photos and the Animals tag to other photos, and you wanted all photos tagged with just Animals. If you only had the Animasl tag, then you could just right-click that keyword and choose Edit from the contextual menu and correct the spelling.

if for example you had Animals and Animasl

You could, but you’d still have to manually transfer the tags from the old list (which would still be present) to the new list. Importing a new keyword list does not automatically transfer tagged photos from the existing list to the new list.

Why not export the current keyword list, edit it in e.g. Excel, then reimport it.

You can create and edit a keyword list outside of Lightroom and import it into Lightroom, but it will just append to the existing list. So, yes you could do that, but then you’d have to go through the steps outlined above to transfer keyword assignment from your old list to the new list. No easy out.

Is there any way to rearrange keywords in a more convenient form, maybe outside of Lightroom?